Chemical compound

compoundcompoundschemical compoundschemicalchemicalssubstancechemical compositioncompositionchemical compositeschemical species
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.wikipedia
2,058 Related Articles

Chemical substance

chemicalchemicalssubstance
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.
Chemical substances can be simple substances, chemical compounds, or alloys.

Chemical bond

bondbondschemical bonds
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. Chemical compounds have a unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds.
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds.

Atom

atomsatomic structureatomic
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.
Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals.

Chemical formula

molecular formulaformulageneral formula
A chemical formula specifies the number of atoms of each element in a compound molecule, using the standard abbreviations for the chemical elements and numerical subscripts.
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus and minus signs.

Chemical element

elementelementschemical elements
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. Pure chemical elements are generally not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H 2, or the polyatomic molecule S 8, etc.).
When different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical compounds.

Subscript and superscript

superscriptsubscriptsuperscripts
A chemical formula specifies the number of atoms of each element in a compound molecule, using the standard abbreviations for the chemical elements and numerical subscripts.
Subscripts and superscripts are perhaps most often used in formulas, mathematical expressions, and specifications of chemical compounds and isotopes, but have many other uses as well.

Oxygen

OO 2 molecular oxygen
For example, a water molecule has formula H 2 O indicating two hydrogen atoms bonded to one oxygen atom. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds, the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium hydride, PdH x (0.02 < x < 0.58)].
It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.

Chemistry

chemistchemicalApplied Chemistry
Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service.
Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.

Ionic compound

ionicionic solidionic crystals
In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding.

Coordination complex

coordination chemistrycomplexcomplexes
Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or the subset of chemical complexes that are held together by coordinate covalent bonds.
Many metal-containing compounds, especially those of transition metals, are coordination complexes.

Non-stoichiometric compound

non-stoichiometricnonstoichiometricnonstoichiometric compound
For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds, the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium hydride, PdH x (0.02 < x < 0.58)].
Non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers; most often, in such materials, some small percentage of atoms are missing or too many atoms are packed into an otherwise perfect lattice work.

Hydrogen

HH 2 hydrogen gas
For example, a water molecule has formula H 2 O indicating two hydrogen atoms bonded to one oxygen atom.
However, hydrogen is the third most abundant element on the Earth's surface, mostly in the form of chemical compounds such as hydrocarbons and water.

Molecule

molecularmoleculesmolecular structure
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or the subset of chemical complexes that are held together by coordinate covalent bonds. Pure chemical elements are generally not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H 2, or the polyatomic molecule S 8, etc.).
A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with oxygen (O 2 ); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (H 2 O).

Diatomic molecule

diatomicdiatomic moleculesdi-
Pure chemical elements are generally not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H 2, or the polyatomic molecule S 8, etc.).
The homonuclear diatomic gases and noble gases together are called "elemental gases" or "molecular gases", to distinguish them from other gases that are chemical compounds.

Chemical reaction

reactionchemical reactionsreactions
A compound can be converted to a different chemical composition by interaction with a second chemical compound via a chemical reaction.
In a substitution reaction, a functional group in a particular chemical compound is replaced by another group.

Chemical structure

structureconformationstructurally
Chemical compounds have a unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds.
In determining structures of chemical compounds, one generally aims to obtain, minimally, the pattern and multiplicity of bonding between all atoms in the molecule; when possible, one seeks the three dimensional spatial coordinates of the atoms in the molecule (or other solid).

Glossary of chemical formulae

List of organic compoundsDictionary of chemical formulas
This is a list of common chemical compounds with chemical formulae and CAS numbers, indexed by formula.

Electronegativity

electronegativeelectropositiveelectronegativities
Elements that fall close to each other on the periodic table tend to have similar electronegativities, which means they have a similar affinity for electrons.
This would lead one to believe that caesium fluoride is the compound whose bonding features the most ionic character.

Hydrogen bond

hydrogen bondinghydrogen bondshydrogen-bonding
Hydrogen bonding occurs when a hydrogen atom bonded to an electronegative atom forms an electrostatic connection with another electronegative atom through interacting dipoles or charges.

Molecular entity

molecular entities
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.

Homonuclear molecule

homonuclearhomonuclear diatomic moleculesTwo atoms of the same element
Two atoms of the same element bonded in a molecule do not form a chemical compound, since this would require two different elements.

Water

H 2 OHOliquid water
For example, a water molecule has formula H 2 O indicating two hydrogen atoms bonded to one oxygen atom. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds, the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium hydride, PdH x (0.02 < x < 0.58)].

CAS Registry Number

CAS numberCASCAS RN
Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service.

Chemical Abstracts Service

Chemical AbstractsCASCASSI
Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service.

Covalent bond

covalentcovalentlycovalently bonded
Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or the subset of chemical complexes that are held together by coordinate covalent bonds.